The field of the present invention is devices for protecting battery electrodes.
Dry cell batteries typically used for portable devices such as flashlights, toys and the like are cylindrical and are provided with a center electrode and a terminal electrode. The center electrode is usually formed as a pin like protrusion having a diameter which is much smaller than the outside diameter of the battery. This center electrode usually forms the positive pole. At the other end of the battery, a terminal electrode is formed which is shaped as a flat contact plate having a much larger diameter than the center electrode. Frequently, the batteries are arranged physically as well as electrically in series in that the center electrode of a first battery directly contacts the terminal electrode of a second battery. If more than two batteries are provided, the center electrode of the second battery directly contacts a terminal electrode of a third battery and so on.
In a flashlight for example, an electrical circuit is typically established from one electrode of a battery, e.g. the center electrode of the foremost battery, through a conductor to a switch, and then to one electrode of the lamp bulb. After passing through the filament of a lamp bulb, the electric circuit emerges through a second electrode of the lamp bulb in electroconductive contact with a conductor, which in turn is etectroconductively connected with the flashlight housing. The flashlight housing itself when made of metal, or a conductor extending along the inner side of the housing, e.g. if the housing is made of plastic, typically provides an electroconductive path to an electrical conductor, generally a spring element, which is in contact with the other electrode of a battery, i.e. typically the terminal electrode of the rearmost battery. Actuation of the switch to complete the electrical circuit enables electrical current to pass through the filament, thereby generating light which is typically focussed by a reflector to form a beam of light.
In the case of medium and larger sized batteries or rechargeable storage batteries, which are often used in flashlights for public safety purposes by police and fire protection personnel, the electrodes of the batteries may be deformed by physical impact to which the flashlight may be subjected. On the one hand, the terminal electrode might be deformed since it comprises a relatively large diameter and, therefore, a low rigidity. On the other hand, the center electrode might be deformed since it is subjected to a relatively high compressive stress due to it's small diameter. In particular, it often happens that besides a deformation of the pin like protrusion itself another deformation pushing the whole pin like protrusion along the center axis of the battery takes place. Although the problems above can occur if only two batteries are connected in series, the electrodes are even more likely to be deformed if a column consisting of a larger number of batteries is provided, e.g. a column of four or five batteries, since the weight of the battery column is larger when more batteries are provided. Therefore, the impact shock received by the electrodes is increased with greater numbers of batteries. The probability of a deformation is still higher if heavier batteries comprising a larger outside diameter are used since in this case the impact shock is still further increased. If an extensive deformation of the electrodes has taken place, the rearmost electrode might loose contact with the rearmost conductor which is generally a spring conductor, or the foremost electrode might loose contact with the conductor connected to one of the two electrodes of the lamp bulb. Moreover, it is possible that the electrodes of the batteries will loose contact with each other so that they are spaced with respect to each other in lengthwise direction. In this case, the electric circuit is no longer closeable and therefore the lamp bulb can no longer be switched on.